The Best Portable Solar Battery Charger

Our former pick, the Anker PowerPort Solar Lite, is being discontinued. After a fresh round of testing, we’ve fully rewritten this guide and added some new picks.

Your guide

Sarah Witman

After spending more than 60 hours testing 12 models, we found that the BigBlue 3 USB Ports 28W Solar Charger is the best portable solar charger for people who want to power a phone or small device off the grid or in an emergency. In addition to being easy to pack and water-resistant, its unique four-panel, three-port design helped it deliver more power to more devices than any other model we tested.

Buying Options

The BigBlue 3 USB Ports 28W Solar Charger produced the most power of any portable solar charger we’ve tested, yet it’s still small and light enough to fit into any camping backpack, hiking daypack, or emergency kit. Although other models nearly matched our pick for power and size, the Big Blue has unique features that make it more versatile and durable, including a third output port and weatherproof port protectors.

You should also plan to buy a USB battery pack or USB-C battery pack—we have recommendations to fit a variety of needs. Solar chargers produce power that can be passed to dying gadgets, but there’s no way to store that power for later. Used with a battery pack, you can take advantage of the sun during the day and recharge your devices overnight. We don’t recommended an all-in-one solar panel and battery as a compromise option because they charge too slowly, store too little energy, and cost too much for what you get.

Why you should trust us

I spent roughly 30 hours researching and testing portable solar chargers for this guide on top of the 30 hours clocked by other Wirecutter staffers over the past two years. Before working at Wirecutter, I was a science writer and fact checker for 4+ years. Plus, during a month-long visit to rural Malawi, I got firsthand experience with a subpar portable solar charger—it was so slow that I tossed it midway through the trip. The editor of this guide, Mark Smirniotis, has written the bulk of our guides to batteries and charging.

Who should get this

The BigBlue’s four panels and three output ports helped it edge out competitors in our testing. Photo: Rozette Rago

USB solar chargers are a great option if you’re taking an extended camping trip or if you’re traveling somewhere with an unreliable power grid. They’re also good for stashing in an emergency kit. In all those specific situations, a solar charger could charge a phone the size of an iPhone X in a few hours of midday sun. But in most situations, a USB solar charger isn’t actually the best portable power source, and you may be better off starting with a USB battery pack, USB-C battery pack, or AC battery pack. Our largest USB battery pick will keep a smartphone charged every night for a week and is smaller than a paperback novel—and it’s not dependent on the weather.

But whether you choose a solar charger or battery, they only work with USB or USB-C devices, which limits their appeal for those who need them for long-term, off-grid setups. If you’re going to be mostly stationary and need to charge or run larger devices like laptops or televisions, or if you need to use more sophisticated communications equipment, you’ll probably be more interested in the larger setups from companies like Goal Zero or even Suntactics. We touch on that kind of gear in our guide to portable AC power stations and hope to expand coverage of them in the future.

How we picked

Photo: Rozette Rago

To decide which solar chargers we wanted to test, we started with a pool culled from Amazon’s best-selling and top-reviewed listings, recommendations from authoritative review sites like Outdoorgearlab.com, and any mentions on sites that specialize in tech or outdoor gear. Bad overall ratings or poor scores on Fakespot.com weren’t automatic dealbreakers, but we axed any models with a pattern of bad reviews—problems like inconsistent and slow performance, warping and bowing, or power-relateddefects. Before calling in any models for testing, we considered these key features:

Power output and charging

We only considered USB solar chargers rated at 10 W or higher because with anything less you may not get enough power all day to charge a single phone, which just isn’t practical. While we preferred those that claimed to offer even more power, they couldn’t come with a major increase in size that would limit the portability.

We skipped any chargers that only had a single USB charging port. We preferred two output ports, which lets you charge a second device or share the power with someone else. Any extra ports were an added bonus. Each port had to draw at least 1 A, which is the minimum needed to fully charge a phone like the iPhone X in three to four hours.

Our pick, the BigBlue 3 USB Ports 28W Solar Charger, is not much bigger than an iPad and can be easily stowed in most daypacks. Photo: Rozette Rago

Size

A good portable solar charger can easily be folded up and stowed away in a daypack—ideally it should not be much bigger than an iPad. At the same time, more surface area is better at capturing elusive rays on a cloudy day, so we discounted models with fewer than two panels. (In previous tests, we saw poor results with small, brick-style models—see our last entry in the Competition section.) And since backpackers or hike-in campers are the most likely to need a solar charger, we didn’t want it to add too much weight to a pack. Every model we tested weighed around a pound, and we didn’t consider anything over two pounds.

Warranty and reliability

We looked at the company websites and contacted customer support to make sure each model was made and distributed by a reputable brand, was readily available to buy, was unlikely to go out of stock quickly, and was under warranty for at least a year.

Extras

If a charger came with any bonus features, we took those into account as well. Features like a magnetic closure or a built-in kickstand can make a solar charger easier to use, but only if it’s already great at its core job of producing power and charging devices. Most of the chargers we tested included a USB–to–Micro-USB cable, but some (like Anker’s 3-foot cable) were longer or felt more durable than others. Many included a few carabiners, too. The carabiners themselves were small and chintzy across the board, but we appreciated the added ability to hang the charger from a backpack or tent.

Price

Solar chargers that cost more than $100 either don’t offer any notable advantages over sub-$100 models, or are in a completely different size and weight class that would be overkill for the casual camper or the average emergency kit. On the other end of the scale, really inexpensive solar chargers generally can’t produce enough power or charge fast enough to be worth bothering with. We’ve struggled with cheap chargers that produce too little power or have inconvenient quirks like those we outline in the Competition section, and we concluded that you shouldn’t rely on them regardless of the situation. That left us with just four models that hit our sweet spot of maximum-output rating, size and weight, availability, and nice-to-have features. We tested the Anker 15 W charger (our former pick, which has since been discontinued) against:

In the past, we’ve also tested nine other models that we discuss further in the competition.

How we tested

We tested the most promising models on a smoggy July week in New York City. If you’re planning to travel closer to the equator or in clearer skies—as we did when testing USB solar chargers in the past—you’ll get more power than we did in our testing. (See our section on How to get the most from your solar charger to juice up performance even more). We conducted head-to-head tests to make sure each charger had the same weather conditions, and we measured each model’s maximum power output, total power produced throughout the day, and how consistent power production was when faced with passing clouds.

On a smoggy day in New York City, each solar charger was only able to produce a fraction of its rated output even at the sunniest point in the day.

Maximum output/fastest charge: We set out the panels just before solar noon, which is when the sun reaches its highest point in the sky at a given location. Making sure the panels were facing the same direction and set up at the same angle, we plugged each one into a PortaPow 3-20V Dual USB Power Monitor andDrok DC 3-21V Load Tester to find just how much power they could produce during the sunniest part of the day.

Total power: We also set all of our candidates up for a four-hour period in the middle of the day so each could charge a fully drained Anker PowerCore 20100. We monitored the cumulative power production with a PortaPow 3-20V Dual USB Power Monitor attached between each solar charger and power bank. When completed, we also drained each power bank using four Drok DC 3-21V Load Testers to double check that our results were accurate. Those numbers let us understand just how charged a standard phone or tablet would be when left out for the same amount of time.

Consistent power: On a different sunny day, we tested that each solar charger could return to full power after being shaded—imitating, say, a cloud passing overhead. Using the same setup, we waited for the power meters to reach at least a few watts, then folded them shut. Once the device readings hit zero, we opened them up again and waited for them to return to full power. All the models in our latest round of testing passed this test, but some solar chargers (especially the cheapest ones) in past tests wouldn’t bounce back—which is a dealbreaker for us. If you decided to leave your phone and solar charger out all afternoon to absorb some juice while you’re off hiking, you’d be pretty disappointed to find your phone had only charged for 15 minutes before a cloud passed by.

A good portable solar charger like our pick should be lightweight and compact when folded and expansive when unfolded. Video: Rozette Rago

Size, fit, and finish: Beyond analyzing performance, we compared the size and construction quality of each model in person. We measured their dimensions when folded and unfolded, and we used a digital kitchen scale to weigh them with precision. Most solar chargers are just 2-4 solar panels sewn to a woven-nylon backing, with wires hidden between the layers and a charging component in a pocket on the end. They usually have a Velcro or magnet closure and are designed with riveted holes or loops around the edges to help you hang or mount the charger to a backpack or tent. All the models we examined had roughly the same quality of stitching and nylon. Since the panels themselves are weatherproof, they’re just sewn in at the edges without any additional covering. The size and weight varied a little between the models, but once we had them all in hand, the basic designs didn’t vary enough that we could rule out any or pick a favorite.

Buying Options

The BigBlue 3 USB Ports 28W Solar Charger is the USB solar charger we’d pack for a week in the woods or a month in Malawi. It produced the most power of the models we tested and offers several standout features—an additional output port, a weatherproof port protector, and an expansive (but lightweight) array of panels to catch every last ray of sunlight.

At the sunniest point of our tests, the BigBlue tied with the X-Dragon 20W SunPower Solar Charger for how much power it produced at any one instant—about 10.7 watts. But over the course of the day, the BigBlue had the highest cumulative wattage: 48.8 watt-hours to the X-Dragon’s 43.7 watt-hours. This isn’t a huge gain—you could barely charge an iPhone X battery halfway with the additional power—but every watt matters if you’re far from an outlet, and the extra power costs little more in size or price.

The BigBlue charger produced more power over the course of a four-hour test day than any other charger we tested.

The BigBlue stood out among the dozens we considered in part because it has two 2.4 A ports and one 1 A port so you can charge three devices simultaneously. (Those ratings are based on the assumption that the solar panels are working at full capacity, which will rarely happen with any solar charger.) Every other model we tested had just two ports. Plus, the ports on the BigBlue are the most protected from water and dust of all the models we tested, as they’re covered by both a cloth flap and rubber cover. Thankfully the cover is connected by a small tether (unlike the Eceen we tested) so you don’t lose it.

The charging ports on the BigBlue are protected from the elements by a rubber flap when not in use. Photo: Rozette Rago

The BigBlue looks attractive, feels sturdy, and is well-made with a weatherproof synthetic fabric. Along with the X-Dragon, which is just as light, it’s one of the lightest models we tested; at 1 pound, 4 ounces, it’s about as heavy as a can of soup. The BigBlue is also one of the smallest models we tested when folded up—tied with the Anker at 11 inches by 6.3 inches. Yet it’s by far the largest when unfolded, with four fold-out solar panels to the X-Dragon’s three (the Anker and Eceen both have just two). This makes the BigBlue a little more cumbersome to use, but the extra surface area is nice for catching every possible ray on a cloudy day.

The BigBlue comes with a two-foot cable to power your gear, which is double the length of the X-Dragon and Eceen cables. That extra foot makes a world of difference if you want to look at your phone while it’s charging or place your power bank safely in the shade while leaving your solar panels exposed to sun. Also included are four carabiners to clip onto the fabric loops sewn around the edges of the BigBlue that you can use to attach it to the outside of a backpack for on-the-go powering or to a tent to charge up your gear while you’re enjoying the day.

Flaws but not dealbreakers

The main downside of the BigBlue is, as its name might suggest, its size. Even though it weighs the same as the X-Dragon, it’s a good 10 inches longer when unfolded, making it a little harder to maneuver into just the right position. But the extra size gives it more surface area to collect the sunshine, and it’s still relatively sleek and compact when packed—that’s when size and weight are most important.

Some models we’ve tested, like the Eceen, snapped closed with two magnets sewn into the material—making it, quite literally, a snap to pack up and stow away. Others, like the X-Dragon, had a little flap of fabric to bind together the edges of the folded-up panels, holding them securely in place with Velcro. By comparison, the BigBlue’s single strip of Velcro was wimpier and came unstuck more easily. We’ve also noticed, in past long-term testing, that Velcro wears poorly in water, mud, and sun in comparison to magnets. Something to keep in mind, but again, not a dealbreaker.

How to get the most from your solar charger

One of the wonderful things about solar power is how simple it can be. The only care and maintenance most panels require is keeping them relatively clean and free of dust. A damp cloth should do the trick most of the time.

To really max out your power output, you’ll want your panels angled correctly. A good rule of thumb is that the panel’s angle, relative to flat ground, should be roughly the same as your latitude, with some minor seasonal adjustments. The farther you are from the poles—and from summer—the steeper the angle. For example, the average angle in Canada’s Winnipeg would be around 41.1 degrees, while it would be around 22.1 degrees in Key West, Florida. Although you might not get the angle exactly right every time, a rough idea could increase your power production by a noticeable amount. If you really want to get the most juice, check sites such as solarpaneltilt.com, PVEducation.org, or Solar Electricity Handbook’s Solar Angle Calculator to figure out the best angle before you go.

Like most solar chargers, the BigBlue includes a pocket on the top flap to store your device while charging. If it’s a hot day, though, that black pocket in direct sunlight is like an oven for your phone. You’d be better off putting your device underneath the panels, or shading it some other way, to prevent it from overheating and shutting down.

The competition

A representative for Anker confirmed that the company is discontinuing Anker’s 15W Solar Charger, our former pick, along with the 14-watt and 21-watt versions. It’s smaller and lighter than the other models we tested, and one of the flattest. It has an attractive, upscale look and comes with a sturdy, three-foot cable. However, it didn’t perform quite as well as the X-Dragon or BigBlue in our tests. We also wish it included at least two carabiners and some additional hanging loops.

The X-Dragon 20W SunPower Solar Charger was second only to our top pick in terms of how much power it produced throughout the day, and it even produced a little more when the sun was at its peak. However, the X-Dragon lacks the convenient extras—like the extra panel, additional charging port, and port protectors—that make the BigBlue stand out as a top pick. Also, it was out of stock on Amazon at the time of publication, and we could not confirm with the manufacturer (AllPowers) that it’s available to buy elsewhere.

Eceen’s ECC-626 13W Solar Charger is light and compact, and it has some nice added features like a fold-out stand, magnetic closure, and neoprene pocket. But it performed significantly worse in our testing than every other model we tested, and we didn’t like that the output ports are located on the outside of the charger—completely at the mercy of the elements. Like the BigBlue, it has a rubber flap covering the ports when they’re not in use, but since it’s not attached by a tether it would be easy to lose, and we almost lost it a few times. We can’t recommend it.

We tested the Goal Zero Nomad 7 since the brand has one of the best reputations for product quality and service in this category. The unit is well-made, features USB and DC charging options, and even has niceties like magnetic closure instead of the Velcro used on cheaper units. But it’s only rated for 7 W (a quarter of the BigBlue’s maximum-output rating) and has a hefty price tag.

While compact, neither the Instapark Mercury 10 nor the now-discontinued Poweradd 14W Solar Charger were able to bounce back to their original charging rates after being shaded for 10 seconds.

The RAVPower 15W Solar Charger used to be our runner-up pick, but RAVPower has replaced it with a 16-watt model, which we haven’t tested because it costs the same as models with much higher maximum-output ratings.